Uplink Feedback Sequencing for Carrier Aggregation Overhead
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Solution Overview
Problem
In LTE-A systems, the existing methods for feeding back data receiving status information are inefficient, leading to high uplink overheads and reduced uplink coverage area, especially in Carrier Aggregation scenarios where multiple Component Carriers require significant feedback, exceeding the capacity of current uplink control channels.
Innovation Solution
The method involves sequencing downlink subframes for each Component Carrier, generating and transmitting receiving status feedback information for the first X downlink subframes, where X is less than or equal to the number of downlink subframes, allowing the base station to perform Hybrid Automatic Repeat Request processing on these subframes while assuming non-receipt of PDCCHs for the remaining subframes, thereby reducing feedback overhead and increasing coverage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If receiving status feedback information for all downlink subframes is transmitted, then measurement precision of data receiving status is improved, but uplink overhead increases
Solution Approach 1:
The patent extracts and transmits only the necessary receiving status feedback information for the first X downlink subframes, omitting feedback for subsequent subframes. This selective extraction reduces the volume of uplink feedback information while maintaining essential HARQ functionality for the most critical subframes.
Solution Approach 2:
Instead of providing complete feedback for all M downlink subframes, the patent implements partial feedback action by limiting the feedback to only the first X subframes where X ≤ M. This partial action approach reduces uplink overhead while maintaining adequate system performance.
2Productivity
If receiving status feedback information for multiple downlink subframes is transmitted collectively, then productivity of feedback process is improved, but device complexity increases
Solution Approach 1:
The patent segments the downlink subframes into two groups: the first X subframes for which receiving status feedback is transmitted, and the remaining M-X subframes for which feedback is not transmitted. This segmentation allows the system to manage feedback complexity by handling different subframe groups differently.
Solution Approach 2:
The patent performs preliminary determination of which downlink subframes require feedback transmission before actual feedback occurs. By pre-establishing that only the first X subframes will have feedback transmitted, the system avoids complex real-time decisions about feedback content, simplifying the overall processing.
3Reliability
If DAI is used to indicate serial number of downlink subframe, then reliability of PDCCH loss detection is improved, but last several lost PDCCHs cannot be detected
Solution Approach 1:
The patent implements a feedback mechanism where the UE feeds back receiving status information on a specific uplink subframe that corresponds to the last downlink subframe that received a PDCCH. This feedback allows the base station to detect whether the UE has lost PDCCHs for the last several downlink subframes, compensating for the limitation of DAI alone.
Data Source
AI summary
An apparatus and a method for feeding back data receiving status, applied to a system, are provided. The method includes sequencing, by a User Equipment (UE), downlink subframes for transmitting data with respect to each Component Carrier (CC), generating receiving status feedback information for the first X downlink subframes with respect to each CC according to the result of the sequencing, where X≤M, wherein M is the number of downlink subframes on each CC, and transmitting the receiving status feedback information generated with respect to each CC to a base station. Accordingly, the UE will not misinterpret the receiving status for the downlink subframes due to inconsistencies with the base station between transmitting and receiving feedback. This affects the Hybrid Automatic Repeat Request (HARQ) transmission, saves the uplink overheads occupied by the receiving status feedback information, and increases the uplink coverage area.